Regarding a technique for ejecting the liquid material in a constant amount, there has hitherto been a problem that, when the ejection is performed for a long time, the liquid material causes a time-dependent change in viscosity thereof and the ejection amount of the liquid material varies.
Recently, with further downsizing and higher-density packaging of chips or with more versatility of application work, there have been not only a demand for continuously performing fine application of the liquid material in a very small amount, but also a need for suppressing a variation in the ejection amount of the liquid material to a lower level. Above all, in the underfill step, even finer application of the liquid material in an even smaller amount is required.
As techniques for coping with the variation in the ejection amount of the liquid material by measuring the amount of the ejected liquid material with the aid of a dedicated measuring device and adjusting the ejection amount based on the measured result, there are known an ejection amount correction method of measuring the weight of the liquid material by using an electronic scale (Patent Document 1), and a device for picking up an image of a droplet of the liquid material and measuring the amount of the droplet based on the picked-up image (Patent Document 2).
Patent Document 1 discloses an ejection amount correction method comprising the steps of periodically measuring the weight of the ejected material, comparing the measured weight with a specified weight, and when the measured weight and the specified weight differ from each other, making control for correcting a number of pulses and a pulse frequency, which are used to drive a pulse motor pump, such that the measured weight comes closer to the specified weight.
Patent Document 2 discloses an application amount adjustment method comprising the steps of registering a target application amount, supplying a gas pressure to a syringe to eject a bond from a nozzle for a trial application, recognizing the bond applied for a trial and calculating the magnitude of the application amount, comparing the calculated trial application amount with the target application amount to determine whether the difference between both the amounts is within an allowable error, and when the difference is not within the allowable error, repeating the above-mentioned steps while changing the magnitude of the gas pressure supplied to the syringe or a time during which the gas pressure is supplied to the syringe.
Patent Document 1: Japanese Patent Laid-Open Publication No. 2002-303275
Patent Document 2: Japanese Patent Laid-Open Publication No. H11-97829